There is a continuing search for materials having desirable fragrance properties. Such materials are sought either to replace costly natural materials or to provide new fragrances or perfume types which have not heretofore been available. Especially desirable qualities for substances having interesting fragrances are stability and persistence in a wide variety of perfumed articles and perfume compositions, ease of manufacture, and intensity of aroma.
Sweet, coumarin-like, herbal, floral, coconut, green, lovage, celery, tagette, and foenugreek-like notes are particularly desirable for many uses in conjunction with perfumes and perfumed compositions and articles.
Various alpha pyrones have been described as being useful in altering the organoleptic characteristics of flavors for foodstuffs as well as fragrances for use in conjunction with perfumed articles.
Arctander, Perfume and Flavor Chemicals (Aroma Chemicals) 1969 contains the following teachings:
I. At No. 1347, the flavor and perfume use of 5-ethyl-alpha pyrone; PA1 Ii. At No. 2230, the flavor and perfume use of 5-methyl-alpha pyrone; PA1 Iii. At No. 2781, the perfume use of alpha pyrone. PA1 I. Lohaus et al., Chemische Berichte, 100, 658 (1967); PA1 Ii. Wiley et al., J. Org.Chem., 22, 1257-9 (1957); PA1 Iii. Belgian Pat. No. 643,891, Aug. 17, 1964; PA1 Iv. Nobuhara, Agr. Biol. Chem. 1969, 33 (9), 1264-9; PA1 V. Pettit et al., J. Org. Chem., 1970, 35 (5), 1398-1404; PA1 Vi. Lamberti et al., Recueil, 86, (1967) 504-510;
Taylor et al. British Pat. No. 748,645, discloses at page 7, lines 105 and 106 the use in butter flavors of the lactones of unsaturated delta hydroxy acids. Sevenants, J. Food Sci., 1971, 36 (3), 536 discloses the occurence of 6-pentyl-alpha-pyrone in peach aroma. Nobuhara, Agr. Biol. Chem, 1969, 33, No. 9, 1264-9 (Title: "Synthesis of Unsaturated Lactones/III: Flavorous Nature of Some delta-Lactones having the Double Bond at Various Sites") indicates the waxey, butter-cake flavor of 6-pentyl-alpha-pyrone at page 1267, col. 1. In addition, the flavor attributes of alpha-pyrones, in general are discussed by Nobuhara.
Methods for the preparation of the alpha pyrones found to be useful in our invention are disclosed as follows:
The 6-alkyl-alpha pyrones of our invention, which are unsubstituted at the "4" position of the pyrone ring may also be prepared according to the process of copending U.S. application for Letters Patent Ser. No. 471,756 filed on May 20, 1974, now U.S. Pat. No. 3,873,574, the reactions of which are as follows. ##STR2## wherein R is alkyl.